The concept of a medical apparatus for humidifying or otherwise treating n gas from an insufflator during surgery is described in Douglas Ott et al. U.S. Pat. Nos. 5,411,474; 6,068,609 and 7,066,902. Briefly, an insufflation gas is heated and hydrated before the gas is directed into a body cavity through a device such as a trocar. In order to hydrate the insufflation gas a charge of hydration fluid is typically injected into a chamber where the hydration fluid can humidify the insufflation gas before the insufflation gas is injected into a body cavity of a patient. Typically, a charge of hydration fluid is injected into a heater hydrator to humidify the insufflation gas as it travels through a chamber in the heater hydrator. When the charge of hydration fluid injected into the heater hydrator is spent or runs low, then a fresh charge may be introduced into the heater hydrator.